All publications herein are incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Hydroformylation is known in the art as a catalytic method for the conversion of an olefin to an aldehyde, wherein the aldehyde has one more carbon than the starting olefin by the addition of a formyl group (CHO) and a hydrogen atom to the carbon-carbon double bond of the olefin. As a result, the molecular weight and the boiling point of the resulting aldehyde are increased relative to the starting olefin. If the olefin contains more than one carbon-carbon double bond, a formyl group (CHO) and a hydrogen atom may be added to each carbon-carbon double bond of the olefin
As is known in the art, the process of hydroformylation requires the use of one or more expensive catalysts. Therefore, in order to reduce catalyst loss, it is advantageous to recover the catalyst from the hydroformylation process. Distillation is often used to recover the hydroformylation catalyst from the hydroformylation process by separating the hydroformylation catalyst from the aldehyde product. During distillation the product stream containing the aldehyde product is heated to a gas so as to separate the aldehyde product from the hydroformylation catalyst. When the boiling point of the aldehyde product is high, a high distillation temperature is needed to obtain good separation efficiency between the aldehyde product and the hydroformylation catalyst. Unfortunately, high distillation temperatures damage the catalyst making it unsuitable for use in subsequent hydroformylation reactions, thereby leading to an increase in catalyst loss.
Methods are known in the art for producing high-boiling point aldehydes. For example, U.S. Pat. No. 6,365,782 B1 describes a hydroformylation process for preparing tricyclodecane dicarbaldehyde and/or pentacyclopentadecane dicarbaldehyde, wherein the tricyclodecane dicarbaldehyde and/or pentacyclopentadecane dicarbaldehyde in the hydroformylation product liquid are extracted with a polyhydric alcohol. However, as discussed therein the dialdehydes react with the polyhydric alcohol used as the extraction solvent to form high-boiling point acetals. The formation of the acetals reduces the yields of the dialdehydes, and in addition, extremely reduces the reaction rate of hydrogenation for producing tricyclodecane dimethanol and pentacyclopentadecane dimethanol, thereby resulting in poor productivity. Further, since the boiling points of the acetals are so close to those of tricyclodecane dimethanol and pentacyclopentadecane dimethanol, they cannot be separated by distillation. To reduce the amount of acetal formation, the addition of one or more tertiary amines was required as described therein.
While methods are known in the art for the preparation of high-boiling point aldehydes by hydroformylation of olefins in the presence of various catalytic systems, further improvements are needed to address various problems associated with separating the high-boiling point aldehyde products from a hydroformylation product solution containing the hydroformylation catalyst, while also reducing the formation of unwanted acetal compounds, particularly without the need to use other substances, such as tertiary amines for reducing the amount of acetal formation. The present invention addresses these needs.